Twenty-two people were arrested during a violent demonstration in Seattle on Monday.
Police officials said people in the crowd committed arson, assault, and obstruction, and failed to disperse.
As officers arrested people, rioters hurled rocks, bottles, and explosives at them, according to the Seattle Police Department.
Video footage showed a number of people dressed in the style favored by Antifa, the far-left, anarcho-communist group, forming a line and facing off with police before officers rushed the line and made arrests.
Intact Molotov cocktails were recovered from the scene.
At one point, a Molotov cocktail was thrown at officers, but it missed and exploded on the road. No one was injured.
The crowd had marched from the International District to the Seattle Police Officer’s Guild building. The guild is a police union. It did not respond to a request for comment.
Two people set fire to the building last month.
“We are in that building and we have to worry,” Jim Fuda, the director of law enforcement services for Crime Stoppers of Puget Sound, told KOMO News. “We know people have been followed home.”
Some people who were in the crowd told the broadcaster that they were peaceful before being dispersed but none were willing to speak on camera.
Warning: Video contains crude language.
The group moved away from the guild building and eventually broke up.
Five more people were arrested later in the night as officers tried impounding a vehicle.
The riot blocked public transportation and all other traffic on 4th Avenue for a few hours, according to the Seattle Department of Transportation.
A traffic camera image appeared to show support vehicles blocking traffic for the group as they moved down the street.